Switching circuit, method and control unit for switching a lighting fixture

ABSTRACT

A switching circuit, method and control unit ( 1 ) for controlling electric power supply for lighting fixtures. The switching circuit has a control unit ( 1 ) with a sensor ( 11 ) for detecting intensity of light reaching the sensor, and a control circuit ( 2 ) for transmitting at least two different switching signals ( 21 - 23 ) at different times in response to the detected light intensity falling below a predetermined twilight value. The circuit further has switching devices ( 34 - 36 ), with a receiver ( 31 - 33 ) for receiving switching signals coming from the output circuit and for selectively generating a switching command for switching on the power supply in response to receiving a switching signal specifically intended for the relevant switching device; and a switching assembly ( 37 - 39 ) connected to the receiver for switching the electric power supply in response to a switching command coming from the receiver.

The invention relates to a switching circuit for switching a lightingfixture. The invention also relates to a method for switching lightingfixtures, as well as to a control unit for application in a circuitaccording to the invention.

A switching circuit is known in practice for remote control of differenthouse lighting, with which a plurality of lighting fixtures in a housecan be switched on or off manually. The known switching circuitcomprises a manually operated remote control provided with keys. Inresponse to the keys being pressed by a user, the remote controlgenerates a switching signal associated with this key. The switchingcircuit further comprises switching devices intended for distributedplacing, with which the power supply for the lighting fixtures can beswitched on and off individually. The switching devices are equippedwith receivers which each respond to a specific switching signal andselectively generate a switching command in response to this switchingsignal, whereby the switch of the switching device switches on or offthe power supply for the lighting fixture connected thereto. When no-oneis present in the house, the lighting fixtures, i.e. the lamps therein,will not be switched on or off, which is an indication to potentialburglars that no-one is at home.

It is also known in practice to switch lighting with a time switch whichhas been manually set by the user, for instance to switch on at 8 p.m.and switch off at 11 p.m. The burning light thus simulates the presenceof an occupant and therefore has a preventive effect against burglary.

A drawback of the use of such time switches is that the presence of theoccupant is not simulated very realistically, since the lights switchedby the switch all go on and off simultaneously at fixed times. It is ofcourse possible to use a plurality of switches, but this istime-consuming and the problem of fixed times is hereby not resolved. Itis an object of the invention to provide a simple solution whereby houseinterior lighting can simulate the presence of an occupant in a morenatural manner.

According to the invention this object is achieved by providing aswitching circuit for controlling electric power supply of lightingfixtures, comprising a control unit with a sensor for detecting theintensity of light reaching the sensor; a control circuit coupled tosaid sensor for transmitting at least two different switching signals atdifferent times in response to the detected light intensity fallingbelow a predetermined twilight value; and at least two switchingdevices, each comprising: a receiver for receiving switching signalscoming from the output circuit and for selectively generating aswitching command for switching on the power supply in response toreceiving a switching signal specifically intended for the relevantswitching device; and a switching assembly connected to said receiverfor switching the electric power supply in response to a switchingcommand coming from said receiver.

A switching circuit according to claim 1 simulates the presence of auser in a more natural manner, since only from a moment at whichdarkness begins to fall to a certain extent are different lightingfixtures switched at different times. The presence of a user is herebysimulated more realistically by the circuit than when all the lightingconnected by the circuit is switched on or off at a fixed time, sincethe time required by a user to make his way to the different electricaldevices is simulated.

The circuit furthermore does not give itself away by already switchingon lighting when it is not yet beginning to get dark, and that it onlycomes into operation some time after it becomes dark is also prevented,whereby the unlit house would begin to become noticeable in the earlyevening between surrounding houses where lights are on. The inventioncan also be embodied in a method as according to claim 11 which formsthe operation of the circuit according to the invention. The inventioncan also be embodied in a control unit as according to claim 12, whichis specifically adapted for application as a component of a switchingcircuit according to the invention. Specific examples of embodimentaspects of the invention are stated in the dependent claims. Furtheraspects, details, effects of the invention are further elucidatedhereinbelow on the basis of examples and the figures shown in thedrawings.

FIG. 1 shows a block diagram of an embodiment of a switching circuitaccording to the invention.

FIG. 2 shows a front view of an embodiment of a receiver for a switchingcircuit according to the invention.

FIG. 3 shows a front view of an embodiment of a control unit accordingto the invention.

The embodiment of a switching circuit shown in FIG. I comprises acontrol unit 1 which can transmit signals 21-23 via a communicationconnection, in this instance an electromagnetic radio frequency (RF)connection. Receivers 31-33 are adapted to receive signals 21-23 fromcontrol unit land at least intended for the relevant receivers.

According to this embodiment the control unit 1 comprises a controlcircuit 2 with a comparator 12 which generates lightintensity-representing signals if the light intensity fulfills apredetermined condition in the space in which a sensor 11 of controlunit 1 connected to comparator 12 is situated. Control circuit 2 isadapted to generate switching instructions at different times inresponse to the signals representing light intensity. These switchinginstructions are converted by an output circuit into switching signalswhich are transmitted. According to this embodiment, the output circuitcomprises a radio transmitter 16, so that the switching signals can betransmitted as radio frequency signals. Receivers 31-33 form part ofswitching devices 34-36 placed in distributed manner in an interior of ahouse. Each of the receivers 31-33 is operatively connected to anassociated member of switching assembly or switches 37-38 betweencontacts 40, 41 respectively 42 and 43, 44 respectively 45, which areadapted for inclusion in a power cable to or from a lighting fixture.

It is noted that switching devices suitable for switching lightingfixtures can of course also be used to switch other domestic electricalappliances such as radios, televisions or electric motors for operatingcurtains or sunblinds, which can likewise simulate the presence ofoccupants when switched on and off. Twilight sensor 11 can measure thelight intensity of light incident upon twilight sensor 11 and generatean intensity signal to comparator 12 which corresponds with the measuredintensity. On the basis of the intensity signal, comparator 12determines the measured light intensity and compares this intensity to apredetermined, optionally adjustable value. Twilight sensor 11 can forinstance be a photoelectric cell which generates to comparator 12 anelectric current which is related to the intensity of light incidentupon the photoelectric cell.

Comparator 12 can for instance be a differential amplifier where avoltage proportional to the magnitude of the current outputted by thephotoelectric cell is supplied to the positive input and a referencevoltage, which defines the twilight value and can be optionallyadjustable, is supplied to the negative input of the differentialamplifier. The positive input of the differential amplifier can forinstance be connected to the output of the photoelectric cell and aresistor can connect the positive input to earth, so that the voltagedrop over the resistor, and therefore the magnitude of the voltage atthe positive input, is proportional to the magnitude of the current fromthe photoelectric cell.

When the light intensity lies above the twilight value, the voltage dropover the resistor will be greater than the reference voltage due to thecurrent from the photoelectric cell, and the differential amplifier willsupply a positive voltage to the amplifier output. If the lightintensity is below the twilight value, the voltage drop will be smallerthan the reference voltage and the differential amplifier will supply anegative voltage to the amplifier output. In this case the voltagesupplied by the amplifier is the signal representing the lightintensity, which indicates whether the light intensity is above or belowthe limit value. A plurality of differential amplifiers and logiccircuits for instance can otherwise provide different limit values as itbecomes light and dark. In this manner lighting fixtures with a lowlight-emitting capacity can for instance be switched on as twilightbegins and, as it becomes darker, brighter lighting fixtures can beswitched on. A further improved simulation of the presence of a user ishereby obtained, since usually the user first requires a littleartificial light and switches on more artificial light as it growsdarker.

In the shown embodiment control circuit 2 comprises an encoder 14 whichis connected communicatively to comparator 12. Encoder 14 is connectedto a display 13, a keyboard 15 and a transmitter 16. When the activatingsignal is received by encoder 14 via the communicative connection tocomparator 12, encoder 14 generates coded switching instruction signals.These coded switching instruction signals are supplied to transmitter16. Transmitter 16 converts the coded signals into switching signals21-23 for receivers 21-33, in the shown embodiment in the form of radiosignals. It is noted that the switching signals can also be transmittedin other manner, for instance via cables, such as the cables of themains electricity in the house.

In the shown embodiment encoder 14 generates a specific and unique codedsignal individually for each of the receivers 31-33 in the switchingcircuit. The switching signals are transmitted on the same frequency,thus reducing the chance of interference of or by other signal sources,for instance mobile phones, other units of the switching circuit asproposed or otherwise. The switching signals are coded so as to bedistinguished from each other by means of different coded signals. Eachof receivers 31-33 actuates a switching assembly, in the embodiment aswitch 37-39, in response to a specifically coded switching signalassociated with the specific receiver 31-33. Receiver 31 can forinstance only actuate when a digital code ‘01’ is received, receiver 32only when a digital code ‘10’ is received and receiver 33 only when adigital code ‘11’ is received.

The receivers 31-33 in the embodiment thus undertake no action as longas the switching signal associated with the specific receiver has notbeen received. It is however also possible to use switching signalswhich differ in other respects. Each receiver 31-33 can for instancerespond only to a switching signal on a different frequency.

In the embodiment of FIG. 1, each of the receivers 31-33 comprises aninput circuit (not shown) for receiving switching signals coming fromoutput circuit 16 and for generating a switching command for switchingon the power supply in response to a switching signal specificallyintended for the relevant switching circuit. In the embodiment of FIG. 1the input circuit comprises a decoder (not shown). The decoder candecode coded switching signals and derive therefrom whether the specificswitching signal is intended for the relevant switching device.

When, according to the decoder, the switching signal is intended for theswitching device in question, the decoder generates a switching commandto switch 37-39 which is connected to the decoder in receiver 31-33. Inresponse to the switching command thus originating from receiver 31-33,switch 37-39 then switches the electrical power supply, in theembodiment of FIG. 1 by breaking or opening the connection betweenelectrical contacts 40,43 respectively 41,44 respectively 42,45.

In response to a light intensity representing light intensities belowthe limit value, encoder 14 can for instance generate the coded signalsin a fixed sequence at fixed time intervals, which may or may not be thesame as each other. In that case the lamps switched by switches 31-33are switched on or off in a fixed sequence with a fixed time betweenswitching of successive lamps. There can for instance be a fixed timeinterval of 5 seconds to 1 minute between the coded signals 21-23intended for different switching devices. A different time interval ishowever also possible. Encoder 14 can also generate the coded signals indifferent sequences with variable time intervals, for instance in arandom sequence with a random time lag between switching of successivelamps.

In the embodiment of FIG. 1 the control circuit 1 distinguishes betweentwo signals representing light intensity, which represent lightintensity above and below a determined limit value. The control circuitcan however also be embodied to provide a plurality of signalsrepresenting light intensity which are linked to a plurality of limitvalues. The control circuit can for instance provide a first signalrepresenting light intensity as a first degree of darkness is reached,and transmit switching instructions whereby some of the lightingfixtures or other connected electrical devices are switched on. When asecond twilight value is reached which is lower than the first twilightvalue, i.e. it has become darker in the space, the control circuit cangenerate a second signal representing light intensity whereby one ormore of the electrical devices not yet switched-on are switched on.

The simulation of the natural behaviour of a user is hereby improvedfurther, since a user will often first switch on only a number of thelamps present in a space in the case of half-light, and will switch onmore lamps as it becomes darker.

The control circuit can comprise a twilight detector for providing afirst signal if the light intensity falls below a predetermined lowervalue and for providing a second signal if the light intensity risesabove a predetermined lower value; and a timer which determines the timelapse between the first signal and the second signal and stores therecorded time duration in a memory. When a signal representing lightintensity is then received again which indicates a fall of the lightintensity below the limit value, the control circuit generates aswitching instruction and starts a timer. When a period of time has thenelapsed which has a preset relation to the value of the recorded timeduration stored in the memory, a switching signal is once againgenerated whereby one or more of switching devices 31-33 opens switch37-39 to switch off the lighting fixture connected thereto. A furtherimproved simulation of the presence of a user is hereby obtained, sincethe user will usually go to bed at a determined time after sunset (andthus after the space becomes dark) and will switch of the lights, thistime being longer as the time from sunset to sunrise grows longer.

It is noted that a system wherein the control circuit is coupled to thesensor for sensing the increase in the detected light intensity above apredetermined lower value; further comprising: a timer for recording theduration of a time interval between the fall in the detected lightintensity below the predetermined twilight value and the increase in thedetected light intensity above a predetermined lower value, or viceversa, and wherein the control circuit and the timer are adapted andcoupled to determine at least one point in time of one of said switchinginstructions after the fall of the detected light intensity below thepredetermined twilight value and previously to the detected lightintensity increasing above a predetermined lower value, subject to therecorded duration of the time interval, can advantageously also beapplied for switching a single lighting fixture or a single group oflighting fixtures if the switching circuit comprises only one switchingdevice or only one switch for switching a lighting fixture, as well aswhen the switching circuit comprises a plurality of switching devicesbut these can only all be switched on and off simultaneously sinceprovisions for separate switching of (a number of) the switching devicesare unavailable. The control unit can optionally also be provided with aclock and setting means for generating a switching instruction at apreset time. The clock can then be set for instance to a point in timeat which the user will switch on a television, such as for instance atthe start of a news broadcast or a particular television programme.

In the embodiment of FIG. 1 encoder 14 is connected communicatively todisplay 13. Encoder 14 can provide display 13 with status informationwhich is then shown on the display. Encoder 14 can for instance show ondisplay 13 which lamps are switched on. Encoder 14 is also connectedcommunicatively to a group of keys 15. By means of keys 15 a user canactivate or deactivate the control unit, in the shown embodiment byswitching the encoder on or off. The keys can also be embodied formanually transmitting signals to the relevant receivers, so that thecontrol unit can also function as remote control for the lamps.

The control unit and the switching devices can be embodied in any waysuitable for the specific application. As for instance shown in FIG. 2,the switching device can be incorporated in an adapter plug 200. Adapterplug 200 is particularly suitable for application in an existingsituation. Adapter plug 200 comprises a housing with a wall socket 203with pin holes 204, 205. A plug of an electrical appliance, for instancea lighting fixture, can be placed in wall socket 203. Via a switch 201the pin holes are electrically connected to plug pins 207, 208 of a plugpart 206 of the housing. Plug part 206 can be placed in a wall socket sothat electrical power can be supplied to the lamp in the lightingfixture via wall socket 203.

In an open position the switch 201 breaks the electrical connectionbetween plug 206 and wall socket 203. In a closed position the switch201 opens the electrical connection. A receiver 31 can control theposition of switch 201 via a control terminal of switch 201 (see FIG.1). When receiver 31 receives the switching signal, receiver 31 changesthe position of switch 201 so that the electrical contact between theplug and the wall socket is broken or opened, and the lamp can thus beswitched on or off.

Receiver 31 can be switched on or off via a key 202 and is alsoconnected to a lamp (or LED) 209 which indicates whether receiver 31 isswitched on. Receiver 31 is also connected to a status display, in theembodiment a lamp (or LED) 210 which can light up depending on whetherthe receiver is switched on or off. Lamp 210 is connectedcommunicatively to switch 201 and can indicate the position of switch201.

FIG. 3 shows an example of a remote control 100 with a control unit 1according to the invention. Remote control 100 has a keyboard 105 withkeys 101-103 with which a plurality of lamps can be remotely switched onor off manually. Keyboard 105 also has a control key 104 whereby controlunit 1 can be switched on or off. The status of the control unit isshown by means of a lamp (or LED) 106 which is on when the control unitis switched on.

The invention is not limited to the above described embodiments. Afterreading of the foregoing a skilled person will be able to derivevariants directly and unambiguously from the shown examples. It will forinstance be apparent that a different number of signals or receivers canbe used than are shown in the embodiments. It will also be apparent thatthe signals can be of any type suitable for the specific implementation,such as for instance (ultrasonic) sound signals, electrical signals,electromagnetic signals or otherwise.

It will also be apparent that, in addition to or instead of the twilightsensor, other sensors can be applied, such as for instance fire sensorsor intrusion sensors. The sensors can, also or instead, detect aphysical parameter other than the light intensity and be for instancepyroelectric sensors, vibration sensors, ultrasonic sensors, radarsensors, mechanical sensors, radio-active sensors, biological sensors orotherwise.

It will also be apparent that components of the circuit with a differentfunction can be implemented physically as a single element. In theembodiment of FIG. 1 for instance, the control device and the outputdevice can be implemented as a single integrated circuit.

It will also be apparent that a power supply device with a switchingdevice in a switching circuit according to the invention can beintegrated into a lighting fixture. The word ‘comprising’ does notpreclude one or more other elements than those stated from beingpresent.

1. Switching circuit for controlling electric power supply for alighting fixture, comprising a control unit (1) with a sensor (11) fordetecting an intensity of light reaching the sensor; a control circuit(2) coupled to said sensor for transmitting at least two differentswitching signals (21-23) at different times in response to the detectedlight intensity falling below a predetermined twilight value; and atleast two switching devices (34- 36), each comprising: a receiver(31-33) for receiving switching signals coming from the output circuitand for selectively generating a switching command for switching on thepower supply in response to receiving a switching signal specificallyintended for the relevant switching device; and a switching assembly(37-39) connected to said receiver for switching the electric powersupply in response to a switching command coming from said receiver. 2.Circuit as claimed in claim 1, wherein the control circuit (2) iscoupled to said sensor (11) for sensing the increase in the detectedlight intensity above a predetermined lower value; which circuit furthercomprises: a timer for recording the duration of a time interval betweenthe fall of the detected light intensity below the predeterminedtwilight value and the increase in the detected light intensity abovethe predetermined lower value, or vice versa, and wherein the controlcircuit (2) and the timer are adapted and coupled to determine at leastone point in time of at least one of said switching signals after thefall in the detected light intensity below the predetermined twilightvalue and before the increase in the detected light intensity above apredetermined lower value, subject to said recorded duration of saidtime interval.
 3. Circuit as claimed in claim 1, wherein the controlcircuit (2) is adapted to generate a first and at least one subsequentswitching signal as switch-on signals for switching on at least twodifferent power supplies.
 4. Circuit as claimed in claim 1, wherein thecontrol circuit (2) and the receivers (31-33) are adapted for wirelesssignal transfer.
 5. Circuit as claimed in claim 4, wherein the receivers(31-33) of the different switching devices (34-36) are adapted toreceive switching signals (21-23) on the same frequency band.
 6. Circuitas claimed in claim 1, wherein the control circuit (2) and the receivers(31-33) are adapted to generate and receive switching signals (21-23)which represent different digital switching codes.
 7. Circuit as claimedin claim 1, comprising a housing in which the control circuit (2) issituated, which housing is also provided with manually operated controlmembers (101-105) for manually operating the control circuit (2). 8.Circuit as claimed in claim 1, wherein at least one of the receivers(31-33) is provided with contact pins (207-208) for placing in a wallsocket and connected to the switching assembly (37-39).
 9. Circuit asclaimed in claim 1, wherein the control circuit (2) is adapted todetermine the different times at which the different switching signals(21-23) are transmitted.
 10. Circuit as claimed in claim 9, wherein thecontrol circuit (2) can be adjusted to set different time durationsbetween successive switching signals (21-23).
 11. Method for switchingat least two lighting fixtures, comprising of: detecting light intensityof ambient light; transmitting at least two different switching signalsat different times in response to a fall in the detected light intensitybelow a predetermined twilight value; receiving the switching signals;and selectively switching at least two different lighting fixtures inresponse to the different switching signals.
 12. Control unit (1) for aswitching circuit as claimed in claim 1, comprising: a sensor (11) fordetecting light intensity which reaches the sensor and a control circuit(2) coupled to said sensor for transmitting at least two differentswitching signals (21-23) at different times in response to fall of thedetected light intensity below a predetermined twilight value. 13.Circuit as claimed in claim 2, wherein the control circuit (2) isadapted to generate a first and at least one subsequent switching signalas switch-on signals for switching on at least two different powersupplies.